The Portal — Richard Bowker

Larry Barnes has made a spectacular discovery-an invisible portal to a parallel universe, where Burger King is Burger Queen, cell phones are huge, and his hometown doesn't look anything like the place where he lives.
When Larry returns, he tells his best friend, Kevin, who convinces him to re-enter The Portal. What could go wrong?
This time, Larry and Kevin enter a world devoid of modern technology, where "America" doesn't exist, and New England is losing a war against Canada and New Portugal. Unable to get back to The Portal, they offer their knowledge to the New England army in order to survive and gain hope of returning home.
But when the ambitious lieutenant using their services discovers just how valuable Larry and Kevin's knowledge is, he changes the plan.
OTHER SCIENCE FICTION TITLES by Richard Bowker
Dover Beach (The Last PI Series, Book 1)
The Distance Beacons (The Last PI Series, Book 2)
Replica
Forbidden Sanctuary
ABOUT RICHARD BOWKER:
Critically-acclaimed author Richard Bowker has published a variety of novels including science fiction, mysteries and thrillers. When he isn't writing, Richard enjoys offering thoughts on writing, reading and learning at www.richardbowker.com